U.S. Department of Justice

Bureau of Alcohol, Tobacco,Firearms and Explosives

Washington, DC 20226

902030:PSB08-0048555.1415400

March 12, 2008

information redacted

Dear name redacted

This is in response to your letter dated November 20, 2007, to the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). You requested that we clarify the explosives regulation at 27 CFR 555.141(a)(10).

According to your letter, you want clarification as to whether the “62.5 grams of total propellant weight” stated in 27 CFR 555.141(a)(10) refers only to the weight of the primary propellant grain or if it also includes the weight of propellant in the delay grain.

The exemptions under 27 CFR 555.141(a)(10) include, in part, model rocket motors that meet all of the following criteria: “Contain no more than 62.5 grams of total propellant weight.” The 62.5 grams of total propellant weight is inclusive of the primary propellant grain and not inclusive of the delay and ejection charges. Therefor, model rocket motors with a primary propellant grain that does not exceed 62.5 grams fall under the exemptions of 27 CFR 555.141.

We trust the foregoing has been responsive to your request. Please feel free to contact the Explosives Industry Programs Branch at (202) 648-7120 if you have additional questions. For additional information, feel free to visit our website at www.atf.gov.

Sincerely yours,

Gary L. BangsChief, Explosives Industry Programs Branch

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Bureau of Alcohol, Tobacco, Firearms and Explosives United States Department of Justice